Signal recording method and apparatus, recording medium and signal processing method

Abstract

A signal recording method for recording a signal having improved sound quality while maintaining interchangeability with the pre-existing format for a digital audio disc or the like. An input signal to a signal recording device is a signal obtained on sampling with the sampling frequency exceeding 4.1 kHz and/or a signal having the number of quantization bits exceeding 16. The input signal is split by a band-splitting filter 3 into a main signal which is a 16-bit signal and a plurality of sub-signals of the frequency range other than the above frequency. Each sub-signal has its priority set by a priority calculating unit 5. The sub-signals are synthesized in the order of the decreasing priority to an inaudible area of the main signal as found by a required bit number calculating unit 4.

What is claimed is: 
     
       1. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized,   wherein the synthesized selected sub-signal is variably scalable during the playback signal of the main signal.   
     
     
       2. The signal recording method as claimed in claim 1 wherein said input signal is an audio signal and wherein the allowable signal area of the main signal which does not affect the playback signal of the main signal on noise superimposition thereon is a psycho-acoustically non-deleterious signal area. 
     
     
       3. The signal recording method as claimed in claim 1 wherein said input signal is a video signal and wherein the allowable signal area of the main signal which does not affect the playback signal of the main signal on noise superimposition thereon is a visually non-deleterious signal area. 
     
     
       4. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is a signal of a broad frequency range sampled at a sampling frequency higher than the sampling frequency of the main signal; and wherein the main signal is a low frequency side signal of the input signal and the sub-signal is a high frequency side signal of the input signal.   
     
     
       5. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is a signal of a broad frequency range sampled at a sampling frequency higher than the sampling frequency of the main signal; and wherein the main signal is a low frequency side signal of the input signal and the sub-signal is a high frequency side signal of the input signal, wherein said input signal is a signal with a sampling frequency of 44.1 kHz or higher and with the number of quantization bits of 16.   
     
     
       6. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein the main signal is a portion of the input signal having a larger weight of quantization of the input signal and wherein the sub-signal is a portion of the input signal having a smaller weight of quantization of the input signal.   
     
     
       7. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein the main signal is a portion of the input signal having a larger weight of quantization of the input signal and wherein the sub-signal is a portion of the input signal having a smaller weight of quantization of the input signal, wherein said input signal is a signal with a sampling frequency of 44.1 kHz and with the number of quantization bits of 16 or higher.   
     
     
       8. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein the input signal is a broad frequency range signal sampled with a frequency higher than the sampling frequency of the main signal, said input signal being also an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein said main signal is the input signal portion with a low frequency range and a large weight of quantization, said sub-signal being the input signal portion with a high frequency range and a small weight of quantization.   
     
     
       9. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized, wherein the input signal is a broad frequency range signal sampled with a frequency higher than the sampling frequency of the main signal, said input signal being also an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein said main signal is the input signal portion with a low frequency range and a large weight of quantization, said sub-signal being the input signal portion with a high frequency range and a small weight of quantization, wherein said input signal is a signal with a sampling frequency of 44.1 kHz or higher and with the number of quantization bits of 16 or larger.   
     
     
       10. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal with a high frequency range. 
     
     
       11. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal with a low frequency range. 
     
     
       12. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal with a large weight of quantization. 
     
     
       13. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal with a small weight of quantization. 
     
     
       14. The signal recording method, as claimed in claim 1 wherein a higher priority is set for the sub-signal having high correlation with the main signal, that is not prioritized. 
     
     
       15. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal having low correlation with the main signal. 
     
     
       16. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal having high entropy. 
     
     
       17. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal having low entropy. 
     
     
       18. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal having a large signal spectral energy. 
     
     
       19. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal having a small signal spectral energy. 
     
     
       20. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal of a long code length obtained on signal compression of the sub-signal. 
     
     
       21. The signal recording method as claimed in claim 1 wherein a higher priority is set for the sub-signal of a short code length obtained on signal compression of the sub-signal. 
     
     
       22. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas; setting priority to each sub-signal; finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal; sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized,   wherein the synthesized selected sub-signal is variably scalable during the playback signal of the main signal.   
     
     
       23. The signal recording method as claimed in claim 22 wherein said priority is set within the sub-signal of a sole unit. 
     
     
       24. The signal recording method as claimed in claim 22 wherein said priority is set within the sub-signals of plural units. 
     
     
       25. The signal recording method as claimed in claim 22 wherein the distance of the unit is the difference of the signal readout sequence from the recording medium. 
     
     
       26. The signal recording method as claimed in claim 22 wherein the distance of the unit is the difference of the signal readout position on the recording medium. 
     
     
       27. The signal recording method as claimed in claim 22 wherein said input signal is an audio signal and wherein the allowable signal area of the main signal which does not affect the playback signal of the main signal on noise superimposition thereon is a psycho-acoustically non-deleterious signal area. 
     
     
       28. The signal recording method as claimed in claim 22 wherein said input signal is a video signal and wherein the allowable signal area of the main signal which does not affect the playback signal of the main signal on noise superimposition thereon is a visually non-deleterious signal area. 
     
     
       29. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is a signal of a broad frequency range sampled at a sampling frequency higher than the sampling frequency of the main signal; and wherein the main signal is a low frequency side signal of the input signal and the sub-signal is a high frequency side signal of the input signal.   
     
     
       30. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is a signal of a broad frequency range sampled at a sampling frequency higher than the sampling frequency of the main signal; and wherein the main signal is a low frequency side signal of the input signal and the sub-signal is a high frequency side signal of the input signal, wherein said input signal is a signal with a sampling frequency of 44.1 kHz or higher and with the number of quantization bits of 16.   
     
     
       31. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein the main signal is a portion of the input signal having a larger weight of quantization of the input signal and wherein the sub-signal is a portion of the input signal having a smaller weight of quantization of the input signal.   
     
     
       32. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein said input signal is an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein the main signal is a portion of the input signal having a larger weight of quantization of the input signal and wherein the sub-signal is a portion of the input signal having a smaller weight of quantization of the input signal, wherein said input signal is a signal with a sampling frequency of 44.1 kHz and with the number of quantization bits of 16 or higher.   
     
     
       33. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein the input signal is a broad frequency range signal sampled with a frequency higher than the sampling frequency of the main signal, said input signal being also an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein said main signal is the input signal portion with a low frequency range and a large weight of quantization, said subsignal being the input signal portion with a high frequency range and a small weight of quantization.   
     
     
       34. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of subareas;   setting priority to each sub-signal;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   finding an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal for recording the main signal to which the sub-signal has been synthesized, wherein the input signal is a broad frequency range signal sampled with a frequency higher than the sampling frequency of the main signal, said input signal being also an enlarged dynamic range signal quantized with the number of quantization bits larger than the above-mentioned number of quantization bits of the main signal; and wherein said main signal is the input signal portion with a low frequency range and a large weight of quantization, said subsignal being the input signal portion with a high frequency range and a small weight of quantization, wherein said input signal is a signal with a sampling frequency of 44.1 kHz or higher and with the number of quantization bits of 16 or larger.   
     
     
       35. A signal recording apparatus comprising: splitting means for splitting the entire area of an input signal into a main area and a plurality of sub-areas and for generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   priority setting means for setting priority for each of the sub-signals of the sub-bands split by said splitting means;   allowable signal area calculating means for calculating, from the main signal as split by said splitting means, an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sub-signal selecting means for sequentially selecting the sub-signals synthesized in said allowable signal range in the decreasing sequence of the priority as set by said priority setting means within the range of the capacity of the allowable signal area as calculated by said allowable signal area calculating means; and   recording means for synthesizing the sub-signal selected by said sub-signal selecting means to the allowable signal area of the main signal as calculated by the calculating means for calculating an allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized,   wherein the synthesized selected sub-signal is variably scalable during the playback signal of the main signal.   
     
     
       36. A signal recording apparatus comprising: unit-forming means for partitioning an input signal in terms of pre-set time units for forming units;   splitting means for splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas for generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   priority setting means for setting priority for each of the sub-signals split by said splitting means;   allowable signal area calculating means for calculating, from the main signal as split by said splitting means, an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sub-signal selecting means for sequentially selecting the sub-signals synthesized to said allowable signal area in the decreasing sequence of the priority as set by said priority setting means within the range of the capacity of the allowable signal area as calculated by said allowable signal area calculating means; and   recording means for synthesizing the sub-signal selected by said sub-signal selecting means to the allowable signal area of the main signal as found by said allowable signal area calculating means for recording the main signal to which the sub-signal has been synthesized, said signal area having a smaller distance of the unit associated with the sub-signal.   
     
     
       37. A signal processing method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area in a signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said allowable signal area in the order of decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal,   wherein the synthesized selected sub-signal is variably scalable during the playback signal of the main signal.   
     
     
       38. A signal processing method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas for generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area, in a signal area of the main signal, noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said allowable signal area in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal;   wherein the synthesized selected sub-signal is variably scalable during the playback signal of the main signal.   
     
     
       39. A data signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion, wherein the synthesized second signal portions are variably scalable during the playback signal of the main signal.   
     
     
       40. An audio signal, comprising: a main area signal comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion;   wherein said allowable signal area of said first signal portion which does not affect the playback signal of the first signal portion on noise superimposition thereon is a psycho-acoustically non-deleterious signal area, and wherein the synthesized second signal portions are variably scalable during the playback signal of the main signal.   
     
     
       41. A video signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion;   wherein said allowable signal area of said first signal portion which does not affect the playback signal of the first signal portion on noise superimposition thereon is a visually non-deleterious signal area, and wherein the synthesized second signal portions are variably scalable during the playback signal of the main signal.   
     
     
       42. A broad frequency range data signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion, said first signal portion sampled at a sampling frequency lower than the sampling frequency of the computer data signal and being a low frequency side-signal of said computer data signal; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion, said second signal portions being high frequency side-signals of said computer data signal;   wherein the synthesized second signal portion is variably scalable during the playback signal of the first signal portion.   
     
     
       43. The data signal of claim 42, wherein said data signal is a signal with a sampling frequency of 44.1 kHz or higher and with the number of quantization bits of 16. 
     
     
       44. An enlarged dynamic range data signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion, said first signal portion quantized with a number of quantization bits lower than the number of quantization bits of the computer data signal; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion;   wherein said first signal portion has a larger weight of quantization of the computer data signal and said second signal portions have a smaller weight of quantization of the computer data signal, and wherein reproduction of the first signal portion can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the first signal portion to which the selected second signal portions have been synthesized results in improved sound quality of the first signal portion.     
     
     
       45. The data signal of claim 44, wherein said data signal is a signal with a sampling frequency of 44.1 kHz and with the number of quantization bits of 16 or higher. 
     
     
       46. A broad frequency range and enlarged dynamic range data signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion, said first signal portion sampled at a sampling frequency lower than the sampling frequency of the computer data signal and being a low frequency side-signal of said computer data signal, said first signal portion quantized with a number of quantization bits lower than the number of quantization bits of the computer data signal; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion, said second signal portions being high frequency side-signals of said computer data signal;   wherein said first signal portion has a large weight of quantization and said second signal portions have a small weight of quantization; and further   wherein the synthesized second signal portion is variably scalable during the playback signal of the first signal portion.   
     
     
       47. The data signal of claim 46, wherein said data signal is a signal with a sampling frequency of 44.1 kHz and with the number of quantization bits of 16 or higher. 
     
     
       48. The data signal of claim 39, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       49. The data signal of claim 40, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       50. The data signal of claim 41, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       51. The data signal of claim 42, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       52. The data signal of claim 44, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       53. The data signal of claim 46, wherein a higher priority is set for the second signal portions with a higher frequency range. 
     
     
       54. The data signal of claim 39, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       55. The data signal of claim 40, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       56. The data signal of claim 41, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       57. The data signal of claim 42, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       58. The data signal of claim 44, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       59. The data signal of claim 46, wherein a higher priority is set for the second signal portions with a lower frequency range. 
     
     
       60. The data signal of claim 39, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       61. The data signal of claim 40, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       62. The data signal of claim 41, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       63. The data signal of claim 42, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       64. The data signal of claim 44, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       65. The data signal of claim 46, wherein a higher priority is set for the second signal portions with a larger weight of quantization. 
     
     
       66. The data signal of claim 39, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       67. The data signal of claim 40, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       68. The data signal of claim 41, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       69. The data signal of claim 42, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       70. The data signal of claim 44, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       71. The data signal of claim 46, wherein a higher priority is set for the second signal portions with a smaller weight of quantization. 
     
     
       72. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a higher correlation with said first signal portion. 
     
     
       73. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a higher correlation with said first signal portion. 
     
     
       74. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a higher correlation with said first signal portion. 
     
     
       75. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a higher correlation with said first signal portion. 
     
     
       76. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a higher correlation with said first signal portion. 
     
     
       77. The data signal of claim 46, wherein a higher priority is set for the second signal having a higher correlation with said first signal portion. 
     
     
       78. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a lower correlation with said first signal portion. 
     
     
       79. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a lower correlation with said first signal portion. 
     
     
       80. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a lower correlation with said first signal portion. 
     
     
       81. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a lower correlation with said first signal portion. 
     
     
       82. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a lower correlation with said first signal portion. 
     
     
       83. The data signal of claim 46, wherein a higher priority is set for the second signal having a lower correlation with said first signal portion. 
     
     
       84. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       85. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       86. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       87. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       88. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       89. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a higher entropy. 
     
     
       90. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       91. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       92. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       93. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       94. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       95. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a lower entropy. 
     
     
       96. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       97. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       98. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       99. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       100. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       101. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a large signal spectral energy. 
     
     
       102. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       103. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       104. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       105. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       106. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       107. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a small signal spectral energy. 
     
     
       108. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       109. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       110. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       111. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       112. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       113. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a longer code length obtained on signal compression of said second signal portions. 
     
     
       114. The data signal of claim 39, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       115. The data signal of claim 40, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       116. The data signal of claim 41, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       117. The data signal of claim 42, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       118. The data signal of claim 44, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       119. The data signal of claim 46, wherein a higher priority is set for the second signal portions having a shorter code length obtained on signal compression of said second signal portions. 
     
     
       120. A signal recording method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesyzing the selected sub-signals to the allowable signal area of the main signal for recording the main signal to which the sub-signals have been synthesized,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       121. The signal recording method, as claimed in claim 120 wherein a higher priority is set for the sub-signal having high correlation with the main signal, that is not prioritized. 
     
     
       122. A signal recording method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority to each sub-signal;   finding an allowable signal area of the main signal in which noise superimposition does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said main signal in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signals to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signals for recording the main signal to which the sub-signals have been synthesized,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       123. A signal recording apparatus comprising: splitting means for splitting the entire area of an input signal into a main area and a plurality of sub-areas and for generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   priority setting means for setting priority for each of the sub-signals of the sub-bands split by said splitting means;   allowable signal area calculating means for calculating, from the main signal as split by said splitting means, an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sub-signal selecting means for sequentially selecting the sub-signals synthesized in said allowable signal range in the decreasing sequence of the priority as set by said priority setting means within the range of the capacity of the allowable signal area as calculated by said allowable signal area calculating means; and   recording means for synthesizing the sub-signal selected by said sub-signal selecting means to the allowable signal area of the main signal as calculated by the calculating means for calculating an allowable signal area of the main signal for recording the main signal to which the sub-signal has been synthesized,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       124. A signal recording apparatus, comprising: unit-forming means for partitioning an input signal in terms of pre-set time units for forming units;   splitting means for splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas for generating a main signal for the main area and a plurality of sub-signals for said sub-area;   priority setting means for setting priority for each of the sub-signals split by said splitting means;   allowable signal area calculating means for calculating, from the main signal as split by said splitting means, an allowable signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sub-signal selecting means for sequentially selecting the sub-signals synthesized in said allowable signal area in the decreasing sequence of the priority as set by said priority setting means within the range of the capacity of the allowable signal area as calculated by said allowable signal area calculating means; and   recording means for synthesizing the sub-signal selected by said sub-signal selecting means to the allowable signal area of the main signal as found by said allowable signal area calculating means for recording the main signal to which the sub-signal has been synthesized, said signal area having a smaller distance of the unit associated with the sub-signal,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       125. A signal processing method comprising the steps of: splitting the entire area of an input signal into a main area and a plurality of sub-areas;   generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area in a signal area of the main signal noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said allowable signal area in the order of decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       126. A signal processing method comprising the steps of: partitioning an input signal in terms of pre-set time units for forming units;   splitting the entire area of the input signal in which the units have been formed into a main area and a plurality of sub-areas for generating a main signal for the main area and a plurality of sub-signals for said sub-areas;   setting priority for each of the sub-signals;   finding an allowable signal area, in a signal area of the main signal, noise superimposition on which does not affect the playback signal of the main signal;   sequentially selecting the sub-signals synthesized to said allowable signal area in the sequence of the decreasing priority within the range of the capacity of the allowable signal area; and   synthesizing the selected sub-signal to the allowable signal area of the main signal having a smaller distance of the unit associated with the sub-signal,   wherein reproduction of the main signal can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the main signal to which the selected sub-signals have been synthesized results in improved sound quality of the main signal.   
     
     
       127. A data signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signals portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion, wherein reproduction of the first signal portion can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the first signal portion to which the selected second signal portions have been synthesized results in improved sound quality of the first signal portion.   
     
     
       128. An audio signal, comprising: a main area signal comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion;   wherein said allowable signal area of said first signal portion which does not affect the playback signal of the first signal portion on noise superimposition thereon is a psycho-acoustically non-deleterious signal area, and wherein reproduction of the first signal portion can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the first signal portion to which the selected second signal portions have been synthesized results in improved sound quality of the first signal portion.   
     
     
       129. A video signal, comprising: a main area segment comprising a first signal portion, said first signal portion having an allowable signal area in which noise superimposition does not affect the playback signal of the first signal portion; and   a sub-area segment comprising a plurality of second signal portions, said second signal portions having predetermined relative priority, each of said second signal portions synthesized to said first signal portion in the sequence of decreasing priority within the range of said allowable signal area of said first signal portion; wherein said allowable signal area of said first signal portion which does not affect the playback signal of the first signal portion on noise superimposition thereon is a visually non-deleterious signal area, and wherein reproduction of the first signal portion can be performed while maintaining device playback interchangability and wherein reproduction of the allowable signal area of the first signal portion to which the selected second signal portions have been synthesized results in improved sound quality of the first signal portion.